Begin by peeling and dicing the Yukon Gold potatoes into uniform pieces. Place them in a large pot and cover with water. Bring to a boil and cook for about 10-15 minutes, or until the potatoes are tender. Drain and set aside.
In the same pot or a Dutch oven, melt the butter over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
Stir in the flour and cook for an additional minute to form a roux, stirring constantly to prevent burning.
Gradually pour in the chicken broth and milk while continuously stirring to avoid lumps. Bring the mixture to a simmer, allowing it to thicken for about 3-4 minutes.
Add the garlic powder, paprika, salt, and pepper to the gravy, adjusting the seasoning according to your taste.
Fold the cooked potatoes into the gravy, gently coating them. Allow the potatoes to simmer in the gravy for 5-10 minutes, enhancing the flavors further.
Once done, remove from heat and transfer the smothered potatoes to a serving dish.
Garnish with chopped green onions just before serving.